ASTM D91-02(2007)e1
(Test Method)Standard Test Method for Precipitation Number of Lubricating Oils
Standard Test Method for Precipitation Number of Lubricating Oils
SIGNIFICANCE AND USE
Fully refined petroleum oils normally contain no naphtha insoluble material. Semirefined or black oils frequently contain some naphtha insoluble material (sometimes referred to as asphaltenes). This test measures the amount of naphtha insoluble material in the oil. This quantity is reported as the precipitation number.
SCOPE
1.1 This test method covers the determination of the precipitation number of steam cylinder stocks and black oils, and can be used for other lubricating oils.
1.2 The values stated in acceptable SI units are to be regarded as the standard.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D91 − 02(Reapproved 2007)
Standard Test Method for
1,2
Precipitation Number of Lubricating Oils
This standard is issued under the fixed designation D91; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
´ NOTE—Deleted Note 1 with reference to naphtha editorially in July 2007.
1. Scope contain some naphtha insoluble material (sometimes referred
to as asphaltenes ). This test measures the amount of naphtha
1.1 This test method covers the determination of the pre-
insoluble material in the oil. This quantity is reported as the
cipitation number of steam cylinder stocks and black oils, and
precipitation number.
can be used for other lubricating oils.
1.2 The values stated in acceptable SI units are to be
5. Apparatus
regarded as the standard.
5.1 Centrifuge Tube, cone-shaped, conforming to the di-
1.3 This standard does not purport to address all of the
mensions given in Fig. 1, and made of thoroughly annealed
safety concerns, if any, associated with its use. It is the
glass. The graduations, numbered as shown in Fig. 1, shall be
responsibility of the user of this standard to establish appro-
clearanddistinct,andthemouthshallbeconstructedinashape
priate safety and health practices and determine the applica-
suitable for closure with a cork. Scale-error tolerances and
bility of regulatory limitations prior to use.
smallest graduations between various calibration marks are
given in Table 1 and apply to calibrations made with air-free
2. Referenced Documents
water at 20°C.
2.1 ASTM Standards:
D4057 Practice for Manual Sampling of Petroleum and
5.2 Centrifuge, meeting all the safety requirements for
Petroleum Products normal use and capable of whirling two or more filled
D4177 Practice for Automatic Sampling of Petroleum and
centrifuge tubes at a speed which can be controlled to give a
Petroleum Products relative centrifugal force (rcf) between 600 and 700 at the tip
of the tubes. The revolving head, trunnion rings, and trunnion
3. Terminology
cups, including the rubber cushion, shall be soundly con-
3.1 Definitions of Terms Specific to This Standard: structed to withstand the maximum centrifugal force capable of
being delivered by the power source. The trunnion cups and
3.1.1 ASTM precipitation number, of lubricating oils, n—the
number of millilitres of precipitate formed when 10 mL of cushions shall firmly support the tubes when the centrifuge is
in motion.The centrifuge shall be enclosed by a metal shield or
lubricating oil are mixed with 90 mL of ASTM precipitation
naphtha, and centrifuged under the conditions of the test. case strong enough to eliminate danger if any breakage occurs.
Calculate the speed of the rotating head by means of the
4. Significance and Use
following equation:
4.1 Fully refined petroleum oils normally contain no naph-
rpm 5 1337 =rcf/d (1)
tha insoluble material. Semirefined or black oils frequently
where:
rcf = relative centrifugal force, and
This test method is under the jurisdiction of ASTM Committee D02 on
d = diameter of swing, in mm, measured between tips of
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.06 on Analysis of Lubricants.
opposite tubes when in rotating position.
Current edition approved July 23, 2007. Published June 2007. Originally
Table 2 shows the relationship between diameter swing, rcf,
approved in 1921. Last previous edition approved in 2002 as D91 – 02. DOI:
10.1520/D0091-02R07E01.
and revolutions per minute.
This test method has been adopted for use by government agencies to replace
Method 3101 of Federal Test Method Standard No. 791b.
3 6. Reagent
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
6.1 Hexanes, Reagent Grade. (Warning—Extremely
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. flammable, harmful if inhaled.)
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D91 − 02 (2007)
least 20 times, allowing the liquid to drain thoroughly from the
taperedtipofthetubeeachtime.Placethetubesinawaterbath
at 32 to 35°C for 5 6 1 min. Momentarily remove the corks to
relieve any pressure, and invert each tube ag
...
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